Observation of mutual diffusion of macromolecules in PS/PMMA binary films by confocal Raman microscopy

The present work proposed a facile approach to quantify macromolecular migration in micrometer thick polymer films. Using a polystyrene (PS)/poly(methyl methacrylate) (PMMA) binary film as the model material, depth profile analysis was conducted by confocal Raman microscopy (CRM). The results showed mutual diffusion of PS and PMMA molecules across the interface of the immiscible polymer pairs when the binary film had been annealed. In addition, both tracer and mutual diffusion coefficients were determined on the basis of the Fickian model, and the factors that influenced the diffusion behavior were discussed. It is believed that the characterization framework established by the authors has theoretical value and practical meaning.